On Mon, Jun 26, 2023 at 04:43:39PM +0800, Tuo Li wrote: > The variables gb_tty->port.close_delay and gb_tty->port.closing_wait are > ofter accessed together while holding the lock gb_tty->port.mutex. Here is > an example in set_serial_info(): > > mutex_lock(&gb_tty->port.mutex); > ... > gb_tty->port.close_delay = close_delay; > gb_tty->port.closing_wait = closing_wait; > ... > mutex_unlock(&gb_tty->port.mutex); > > However, they are accessed without holding the lock gb_tty->port.mutex when > are accessed in get_serial_info(): > > ss->close_delay = jiffies_to_msecs(gb_tty->port.close_delay) / 10; > ss->closing_wait = > gb_tty->port.closing_wait == ASYNC_CLOSING_WAIT_NONE ? > ASYNC_CLOSING_WAIT_NONE : > jiffies_to_msecs(gb_tty->port.closing_wait) / 10; > > In my opinion, this may be a harmful race, because ss->close_delay can be > inconsistent with ss->closing_wait if gb_tty->port.close_delay and > gb_tty->port.closing_wait are updated by another thread after the > assignment to ss->close_delay. And how can that happen? Also you have trailing whitespace in your changelog text :( > Besides, the select operator may return wrong value if > gb_tty->port.closing_wait is updated right after the condition is > calculated. > > To fix this possible data-inconsistency caused by data race, a lock and > unlock pair is added when accessing different fields of gb_tty->port. > > Reported-by: BassCheck <bass@xxxxxxxxxxx> As per the documentation for research tools like this, you need to explain how this was tested. thanks, greg k-h _______________________________________________ greybus-dev mailing list -- greybus-dev@xxxxxxxxxxxxxxxx To unsubscribe send an email to greybus-dev-leave@xxxxxxxxxxxxxxxx
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